L-CARNITINE PLUS FILM COATED TABLET

Indications

• Primary carnitine deficiency
• Secondary carnitine deficiency (e.g., due to certain metabolic disorders)
• Certain conditions associated with impaired fatty acid oxidation
• Supportive treatment in patients with heart disease or metabolic syndrome

Dosage

Children: Refer to BNF for Children for specific dosing recommendations based on the child's condition and age.

Adults: Refer to BNF for specific dosing recommendations based on the condition being treated.

Mechanism of action

Carnitine facilitates the transport of long-chain fatty acids across the mitochondrial membrane by forming acyl-carnitine derivatives. This process is essential for the β-oxidation of fatty acids, enabling their conversion into acetyl-CoA, which enters the citric acid cycle to produce ATP. Additionally, carnitine plays a role in the removal of toxic acyl groups from the mitochondria, thus helping to detoxify the cell.

Pharmacodynamics

Carnitine enhances fatty acid oxidation and energy production in tissues that rely heavily on fat as a fuel source. It helps maintain cellular energy homeostasis, supports metabolic functions, and may have protective effects against oxidative stress by improving mitochondrial function.

Pharmacokinetics

Carnitine is absorbed in the gastrointestinal tract, with peak plasma concentrations typically occurring within 3-5 hours post-ingestion. It is distributed widely in body tissues, with high concentrations found in skeletal and cardiac muscle. Carnitine is primarily excreted in the urine as free carnitine and acyl-carnitine derivatives. The half-life of carnitine in plasma is approximately 2-3 hours, and its levels can be influenced by dietary intake and renal function.

Adverse effects

• Nausea
• Vomiting
• Abdominal cramps
• Diarrhea
• Fishy body odor

Precautions

• Use with caution in patients with renal impairment
• Monitor for changes in renal function

Pregnancy

Safety in pregnancy has not been established.

Breast-feeding

Carnitine is excreted in breast milk; use caution.

Storage

Store in a cool, dry place, protected from light.

Formulations

• Carnitine oral solution
• Carnitine tablets

Indications

• Parkinson's disease
• Dopamine-responsive syndromes

Dosage

Children: Refer to the BNF for Children for specific paediatric dosing information.

Adults: Refer to the BNF for specific dosing guidelines.

Mechanism of action

Levodopa is converted to dopamine by the enzyme aromatic L-amino acid decarboxylase. This conversion occurs primarily in the brain, where dopamine acts on dopaminergic receptors, restoring the balance of neurotransmission that is disrupted in Parkinson's disease.

Pharmacodynamics

Levodopa's pharmacodynamic effects are primarily linked to its conversion to dopamine in the central nervous system. This leads to an improvement in motor symptoms such as bradykinesia, rigidity, and tremor in patients with Parkinson's disease. The restoration of dopamine levels helps to enhance the function of the nigrostriatal pathway, which is crucial for the regulation of movement.

Pharmacokinetics

Levodopa is well absorbed from the gastrointestinal tract, with peak plasma concentrations occurring approximately 1 to 2 hours after administration. It undergoes extensive first-pass metabolism, and its bioavailability is significantly enhanced when combined with carbidopa. The elimination half-life of levodopa is approximately 1 to 2 hours, and it is primarily excreted in the urine as metabolites.

Interactions

• levodopa + linezolid: Severe (increases risk of elevated blood pressure)
• metoclopramide + levodopa: Severe (decreases effects)
• levonorgestrel + ulipristal: Severe (decreases efficacy)
• voxilaprevir with sofosbuvir and velpatasvir + levothyroxine: Severe (increases absorption)
• asenapine + levodopa: Moderate (decreases effects)
• risperidone + levodopa: Moderate (decreases effects)
• entacapone + levodopa: Moderate (increases exposure)
• mao-b inhibitors + levodopa: Moderate (increases effects)
• opicapone + levodopa: Moderate (increases exposure)
• tetrabenazine + levodopa: Moderate (decreases effects)

Pregnancy

Consult specific guidelines as the safety profile of levodopa in pregnancy may vary.

Breast-feeding

Consult specific guidelines as levodopa may pass into breast milk.

Storage

Store in a cool, dry place, away from direct sunlight.